Britain has rejected a prisoner-swap proposal by Iran's foreign minister, calling it a 'vile' diplomatic maneuver.

British Foreign Secretary Jeremy Hunt on April 25 said 'what is unacceptable about what Iran is doing is that they are putting innocent people in prison and using it as leverage.'

The previous day, Iranian Foreign Minister Mohammad Javad Zarif suggested a swap between Nazanin Zaghari-Ratcliffe, a British-Iranian citizen who is in prison in Tehran after being convicted of sedition, and Negar Ghodskani, an Iranian citizen being held in Australia on a U.S. extradition warrant.

Zaghari-Ratcliffe's husband, Richard Ratcliffe, said the idea was 'almost impossible' and not the 'way forward.'

Zaghari-Ratcliffe, who works for the Thomson Reuters Foundation, was visiting relatives in Iran when she was arrested in 2016. She was accused of antigovernment activities and sentenced to five years in prison.

Ghodskani was arrested in 2017 after the United States accused her of seeking restricted U.S. communications technology by posing as an employee of a Malaysian company.

The United States believes she intended to transfer the technology to an Iranian firm.

Hurt said there was a 'huge difference' between the two cases.

'The woman in jail in Australia is facing due process, a proper legal procedure, and she is alleged to have committed a very serious crime,' he said. 'Nazanin Zaghari-Ratcliffe is innocent -- she has done nothing wrong.'